Process of and electrolytes for bright nickel electroplating



United States Patent 3,428,536 PROCESS OF AND ELECTROLYTES FOR BRIGHT NICKEL ELECTROPLATING Jack 'C. Towle, East Cleveland, Arthur H. Du Rose, Cleveland, William H. Meek, Jr., Euclid, and Dale G. Block, Parma, Ohio, assignors to Kewanee Oil 'Company, Bryn Mawr, Pa., a corporation of Delaware No Drawing. Filed May 9, 1966, Ser. No. 553,001 U.S. Cl. 204-49 15 Claims Int. Cl. C23b 5/08 ABSTRACT OF THE DISCLOSURE This invention relates to electroplating with nickel. More specifically it relates to the electrodeposition of fully bright and ductile nickel plate. Still more specifically, it relates to nickel plating processes using allenic compounds as the brightening agent in the plating bath. This invention also relates to new allenic compounds which are useful as brightening agents in nickel plating baths.

While various olefinic compounds have been suggested for use as brightening agents in nickel plating baths, none of these have been found to be sufliciently suited for this purpose to warrant commercial use thereof with the exception of allyl sulfonate which is a different class of addition agents from those covered herein.

In accordance with the present invention, it has been found that the cumulative effect of adjacent double bonds, as found in allenic compounds makes such compounds particularly elfective for this purpose. Moreover, certain of these allenic compounds which have been found to be particularly useful as brightening agents also exhibit pronounced leveling effects.

The allenic compounds found to be particularly suitable as brightening agents in nickel plating baths are defined by the formula:

R R R-( J=C=( 1X wherein R is hydrogen or methyl,

ice

wherein R' is hydrogen or an alkyl radical of 1-4 carbon atoms, or two Rs can be aliphatic hydrocarbon divalent radicals joined to form a six-membered cycloaliphatic ring with the carbon of the formula,

R" is hydrogen or an alkyl radical of 1-4 carbon atoms,

R' is a divalent saturated aliphatic hydrocarbon radical of 2-6 carbon atoms,

Ar is phenylene, naphthylene, diphenylene or an alkyl derivative having 1-4 carbon atoms in the alkyl group, and

n is an integer having a value of 1 to 10.

The maximum molecular weight of the respective compounds is limited by the fact that the compounds must have a water solubility of at least 0.02 gram per liter. Generally, however, a molecular weight above 500 is not desirable.

In the practice of this invention, a bright nickel coating is electrodeposited from an aqueous solution of at least one nickel salt in which there is also dissolved at least about 0.02 gram per liter of an allenic compound as defined herein. Generally, no more than 3 grams per liter is necessary for the purpose of this invention. In many cases improved results are obtained when a sulfo-oxygen compound is also used, such as an unsaturated aliphatic sulfonic acid, aryl and aralkyl sulfonic acids, sulfonamides and sulfonimides.

The allenic compounds can be used in various aqueous nickel plating baths such as the standard Watts bath, nickel sulfate baths, nickel chloride baths, and various other baths based on nickel sulfamate, nickel fluoborate and nickel formate. These are mostly acid baths of pH above 2. Alkaline nickel plating baths can also be used although it is generally preferred not to exceed a pH of 8. However for certain purposes a pH as high as 12 can advantageously be used as illustrated hereinafter.

In most of the examples given hereinafter, a standard Watts electroplating bath is used. Such a bath contains 30-50 ounces of nickel sulfate per gallon of solution, 2-15 ounces per gallon of nickel chloride and 2-8 ounces per gallon of boric acid. The pH is adjusted to a range of 25.5 and the bath is operated at a temperature from room temperature to near boiling, preferably about F.

Allenic compounds defined by the above generic formula as being suitable in the practice of this invention include but are not limited to the following:

Various organic sulfo-oxygen compounds are known in the nickel plating art as brighteners of the first class, or as control agents. These can be employed in combination with the allenic compounds generally in an amount of at least about 1 gram per liter. Typical organic sulfo-oxygen compounds suitable for this purpose include but are not restricted to the following:

Unsaturated aliphatic sulfonic acids:

CH CHSO H CHFCHCH SO H Aryl and aralkyl sulfonic acids:

Aryl and aralkyl sulfonimides and sulfonamides:

Example I A standard Watts plating bath containing per liter of solution 280 grams of nickel sulfate, 50 grams of nickel chloride and 40 grams of boric acid is used. To this is added 5 grams per liter of disodium naphthalenedisuliomate and 0.05 grams per liter of 2,2-dimethyl-3,4-pentadienal. The bath is operated at a temperature of F., a pH of 4.0 and a current density of 40 amps per square foot to eifect a bright nickel plating.

Example II The procedure of Example I is repeated using in place of the disodium naphthalenedisulfonate, 2.0 grams per liter of saccharin, and as the allenic compound 0.15 gram per liter of 2,3-butadienoic acid. A bright nickel plating is produced.

Example III The procedure of Example I is repeated with similar results using in place of the disodium naphtha1enedisu1 fonate, a combination of 2.0 grams p,p'-oxy-bis(dibenzene sulfonimide), 0.76 gram of N,N-bis(phenylsulfonyl)- 4,4'-biphenyldisulfonomide, and 0.4 gram of saccharin per liter of solution. As the allenic component there is used 0.05 gram per liter of 1-p-(dimethylaminophenyl)-2,2- dimethyl-3,4-pentadien-1-01.

Example IV The procedure of Example I is repeated with good brightening results using 3 grams per liter of dibenzenesulfonimide and 1 gram per liter of sodium allyl sulfonate instead of 5 grams per liter of disodium naphthalenedisulfonate and as the allenic component 0.05 gram per liter of l-hydroxymethyl-1-allenylcyclohexene-3.

Example V The procedure of Example I is repeated with satisfactory brightening results using no organo sulfooxygen compound and using as the allenic component 0.1 gram per liter of 2-methyl-2,3-butadienyltrimethylammonium chloride.

Example VI The procedure of Example V is repeated using 0.05 gram per liter of 3,6-dioxa-8,9-decadien-l-ol and operating at room temperature. A semi-bright deposit having good leveling properties is produced. Upon repetition of this procedure the luster is enhanced somewhat by the addition of 0.1 ml. per liter of 30% formaldehyde or 1 gram per liter of chloral or 0.04 gram per liter of coumarin.

Example VII An allenic plating bath is used containing 100' grams per liter of NiSO -6H O, 40 grams per liter of tetrasodiumethylenediaminetetraacetate, 60 grams per liter of sodium citrate, 35 grams per liter of NH Cl, and 35 ml. per liter of triethanolamine. Using a temperature of 120 F. and a pH of 8.0, this solution gives a semi-bright deposit at 5-20 amps per square foot, a dull semi-bright deposit at 20-70 amps per square foot, and a dull matte deposit at about 70 amps per square foot. When the same bath is used with the addition of 0.05 gram per liter of 2,2-dimethyl-3,4-pentadien-ol, the deposit in each case is uniformly bright or semi-bright.

Example VIII Satisfactory brightening results are obtained by the procedures of Examples I and V using equivalent amounts respectively of the following compounds:

2,2-diethyl-3,4-pentadienl-al;

2,2-diethyl-3 ,4-pentadien-1-ol;

4-hydroxy-5 ,5 -dimethyl- 1,6,7-octatriene 2,3-butadien-1-ol; 2-ethyl-2-butyI-S-methyl-3,4-hexadienal; l-formyl-1-allenylcyclhexene-3; l-hydroxymethyl-1-allenylcyclohexene-3; and 3 ,6dioxa-8,9-decadienl-ol.

Example IX The procedures of Examples I and V are repeated with satisfactory brightening using, in place of the Watts bath, standard nickel plating baths using nickel sulfamate, nickel fluoborate and a high concentration of nickel chloride respectively as the nickel salt component.

Example X The procedure of Example VII is repeated except that an equivalent amount of 2,3-butadienoic acid is used as the allenic compound and the pH is increased to 12. The resultant deposit is fully bright at current densities in the range of 2 to 10 asf. but becomes duller as the current is increased beyond this range.

In the preceding example it is also found that larger amounts of the allene compound can be used than is ordinarily the case without causing striation in the deposit.

Allenic compounds used in the practice of this invention can be prepared by various methods taught in the prior art, including British Patent 971,751; Bailey & Pfeifer, J. Org. Chem, 20, 1337-41 (1955); Eglinton et al., J. Chem. Soc., 31973200(1954). Typical procedures are given below for various typical compounds.

1-allyl-2,2-dimethyl-3,4-pentadienal A solution containing 0.15 mole of allylmagnesium bromide in 250 ml. of ether isadded dropwise with cooling to a solution of 16.5 g. (0.15 mole) of 2,2-dimethyl-3,4- pentadienal in 30 ml. of ether. After the reaction is complete the mixture is shaken with dilute hydrochloric acid. The ether phase is separated, washed with fresh water and dried over sodium sulfate. Upon evaporation of the ether and distillation of the residue, 8.0 g. of product is collected which boils at -1 C. at 10 mm. Hg. Infrared analysis shows strong absorption at 5.1 microns, Which is characteristic of the allenic group, and strong absorptions for hydroxyl and allyl groups.

1- p-dimethylaminophenyl -2,2-dimethyl-3 ,4-pentadienol An ethereal solution containing 0.1 mole of p-dimethylaminophenyl lithium is added over a 0.5 hour period, at ice bath temperature, to an ethereal solution of 11.0 g. (0.1 mole) of 2,2-dimethyl-3,4-pentadenol. After the reaction is complete the mixture is cautiously hydrolyzed with an excess of water. The ether phase is separated and extracted with dilute hydrochloric acid. The combined extracts are washed with fresh ether and then neutralized with dilute sodium hydroxide. The product is extracted several times with ether and the combined extracts are dried over sodium sulfate. The product is precipitated from ether solution as the hydrochloride salt with anhydrous hydrogen chloride. A white solid, 15.0 g., is collected. Infrared analysis shows strong allenic absorption at 5.1 microns, and strong absorptions for hydroxyl, amino and phenyl groups.

l-formyl-1-allenylcyclohexene-3 A mixture of 23.0 g. (0.41 mole) of propargyl alcohol, 45.3 g. (0.41 mole) of 1-formylcyclohexene-3, 0.1 g. of hydroquinone and 0.1 g. of p-toluene sulfonic acid in 60 ml of benzene is heated at reflux for 5 hours. The water of reaction is collected in a Dean-Stark trap. Fractionation of the mixture affords 22.0 g. of product boiling at 71 C. at 3 mm. Hg. Infrared analysis shows strong absorption for the allenyl, aldehyde and cyclohexene groups.

l-hydroxymethyl-l-allenylcyclohexene-3 To a solution of 10.3 g. (0.07 mole) of l-formyl-lallenylcyclohexene-3 and 7.0 ml. of 40% formaldehyde solution in 25 ml. of methanol is added 8.4 g. of 50% sodium hydroxide solution over 15 minutes at 3550 C. The mixture is then heated at 60 C. for 3 hours and poured into 300 ml. of water. The mixture is extracted with three 50 ml. portions of benzene. The combined extracts are dried over sodium sulfate and distilled. By this procedure, 6.5 g. of product, boiling at -6 C. at 3 mm. Hg is collected. The infrared analysis shows stron absorptions for the allenic, hydroxyl and cyclohexenyl groups.

3 ,6-dioxa-8,9-decadien- 1-01 A mixture of 1.0 g. of powdered potassium hydroxide and 40 ml. of isopropanol is stirred at reflux until the solids are dissolved. The solution is cooled at 25 C. and 10.0 g. (0.143 mole) of 2,3-butadiene-1-ol is added. With agitation, 13.2 g. (0.3 mole) of ethylene oxide is passed into the solution over a 30 minute period. The reaction temperature is maintained at 2535 C. by intermittent cooling. After the addition is complete the mixture is stirred at 40-50" C. for 1 hour and then at 30 C. for an additional 2 hours. The catalyst is neutralized with hydrochloric acid and the mixture is filtered through a bed of Filter Cel. The isopropanol and unreacted 2,3-butadiene-l-ol are distilled from the mixture to a maximum pot temperature of 80 C. at 10 mm. Hg. A dark orange, water soluble oil, 19.5 -g., is obtained. Infrared analysis indicates strong absorption for the allenic, ether, and hydroxyl groups.

New compounds made according to the above procedures include:

4-hydroxy-5,5-dimethy1--1,6,7-octatriene which has the formula:

CH =C=CHC(CH CH(OH) CH CH=CH l-formyl-l,l-allenylcyclohexene-3, which has the formula:

CHz-CHz CHO l-hydroxymethyl-l-allenylcyclohexene-3, which has the formula:

CHz-CHz onion CH-C2 CH=CH=CHz Diethylene glycol mono-2,3-butadienol ether (3,6- dioxa-8,9-decadien-l-ol) which has the formula:

In addition to their utility as brightening agents for nickel plating, the allenic compounds of this invention are useful as corrosion inhibitors, particularly with respect to acidic solutions and vapors.

For use as brighteners in nickel plating the compounds which are particularly efiective and preferred are those of the formula in which X represents the carboXy, hydroxymethyl, 1- formyl-3-cyclohexenyl, 1 hydroxymethyl-3-cyclohexenyl, methylene-trialkyl ammonium halide radicals and radicals of the formula fill wherein R and R" are hydrogen or alkyl radicals of 1-4 carbon atoms and Y is hydroxymethyl, formyl or carboxy, or derivatives thereof such as the polyethylenoxy derivatives of the hydroxymethyl groups.

Since some of these allenic compounds are more volatile than others, agitation of the plating solution by bubbling air therethrongh sometimes causes depletion of the allenic compound by air entrainment. In such cases a lower operating temperature or a mechanical means of agitation may be preferred.

The invention claimed is:

1. The process of nickel plating to a degree of brightness of at least semi-bright comprising the step of electrodepositing a nickel plate from an aqueous solution of a nickel salt containing at least 0.02 gram per liter of an allenic compound having the formula:

R is selected from the class consisting of hydrogen and methyl;

R is a radical selected from the class consisting of hydrogen, an alkyl radical of 1-4 carbon atoms, and an aliphatic divalent hydrocarbon radical two of which are joined to form, with the carbon atom of the formula to which they are attached, a 6-membered cyloaliphatic ring;

R" is selected from the class consisting of hydrogen and an alkyl radical of 1-4 carbon atoms;

R' is a divalent saturated aliphatic hydrocarbon radical of 2-6 carbon atoms;

Ar is a divalent radical selected from the class consisting of phenylene, naphthylene, diphenylene and alkyl derivatives thereof having "1-4 carbon atoms per alkyl group; and

n is a integer having a value of 1-10.

2. The process of claim 1 in which said allenic compound is 2,2-dimethyl-3,4-pentadienal.

3. The process of claim 1 in which said allenic compound is '2,3-butadienoic acid.

4. The process of claim 1 in which said allenic compound is l-p-(dimethylaminophenyl)-2,2-dimethyl3,4- pentadien-l-ol.

5. The process of claim 1 in which said allenic compound is 1-hydroxymethyl 1-allenylcyclohexene-3.

6. The process of claim 1 in which said allenic compound is Z-methyl -2,3-butadienyltrimethylammonium chloride.

7. The process of claim 1 in which said allenic compound is 2,2-dimethyl-3,4-pentadieno-1-ol.

8. The process of claim 1 in which said allenic compound is 2, 2-diethyl-3,4-pentadienal.

9. The process of claim 1 in which said allenic compound is 2,'2-diethyl3,4-pentadieno-l-ol.

10. The process of claim 1 in which said allenic compound is l-allyl 2,2-dimethyl-3,4-pentadieno l-ol.

11. A nickel plating bath comprising an aqueous solution of nickel salt having at least 0.02 grams per liter of an allenic compound having the formula:

R is selected from the class consisting of hydrogen and methyl;

R is a radical selected from the class consisting of hydrogen, an alkyl radical of 1-4 mrbon atoms, and an aliphatic divalent hydrocarbon radical two of which are joined to form, with the carbon atom of the formula to which they are attached, a 6-membered cycloaliphatic ring;

R" is selected from the class consisting of hydrogen and an alkyl radical of 1-4 carbon atoms;

R' is a divalent saturated aliphatic hydrocarbon radical of 2-6 carbon atoms;

Ar is a divalent radical selected from the class consisting 9 10 of phenylene, naphthylene, diphenylene and alkyl de- References Cited rgirijliges thereof having 1-4 carbon atoms per alkyl UNITED STATES PATENTS I n is a integer having ava-lue of 1-10. 2,781,306 12/1957 Brown 20449 12. A nickel plating bath of claim 11 in which said 2,849,353 8/1958 Kflrdos compound is 2,'2-dimethy1-3,4- e mdi 1, 5 3,032,572 5/1962 Flscher et a1. 1 06l1 XR 13. A nickel plating bath of claim 11 in which said 3,133,006 5/1964 et compound is 2,'3-butadienoic acid. I P E 14. A nickel plating bath of claim 11 in which said HOWMD WILL IAMS f xamme" compound is l-p-(dimethylaminophcnyl)-2,'2-dimethyl- 10 KApLANiAssl-Ylam Exammer- 3,4-pentadien-10l.

15. -A nickel plating bath of claim 11 in whicli said compound is l-hydroxymethyl-1-a1leny1cyclohexene-3. 0-5676, 576, 598, 615, 32 

